When you plug these devices into your mac it will recognize storage units: the internal card and the external one. You just have to press on android to connect. Then you can move everything you want.
For updates, you just have to follow the instructions provided around here - download some zip (either in the official site or custom rom, usually has instructions), put those files in the root of the sdcard with the procedure mentioned above, and either it will automatically install or you'll have to go in to the factory menu at boot and tell it to update from those files. It's easy.
Neither windows nor mac, just by plugging the device, will see the system files, just the sdcards, like a camera or cell phone.